Wrapping sheet for oil-slushed metal articles



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M. w. FORREST Filed May 12, 1945 l'nvenor Marsh/all WIFE rz'ea July 27,1.948.

WRAPPING SHEET FOR oIL-sLUsHED METAL ARTICLES Patented July 27, 1948UNITED STATES PATENT oEElcE WRAPPING SHEET FOR OIL-SLUSHED METALARTICLES Marshall W. Forrest, Framingham, Mass., as-

signor to Angler Corporation, Framingham, Mass., a corporation ofMassachusetts Application May 12, 1943, Serial No. 486,726

4 Claims. (Cl. 154-50) This invention relates to `a wrapping sheet foruse on metal parts, such as nely finished parts for airplane engines,which are siushed with oil to protect them during shipment and storage,and

the object is to provide a sheet which' will not accompanying'diagrammatic* andv lunrealistic drawings, wherein:

Fig. l1 is a plan viewcf thesheet with successive-portions broken awayand with a conventional indication of craping; and

Fig. 2 is a diagrammatic cross section, thev l thickness of the variouslayers being exaggerated,

the gure notpurporting to be in any way accurate in its dimensionalproportions.A l

Many greaseproof or oilproof wrappers have been'proposed and used.Wrappers for greasy foods, such, for example, as butter, are familiarexamples. They are Lgenerally applied to a commodity to enclose the same`and the wrapped article is frequently enclosed in a carton or the likefor exterior protection. The greaseproof quality serves to prevent theescape of greasy or oily material to th'e exterior, the purpose beingthe separation of exterior objects and the greasy material. In the caseof oiled machine parts as referred to, it is desirable not only toenclose the oil to prevent it from smearing on an exterior object and toprevent its contamination with dirt but also to preserve the integrityof the film as a protective stratum for the metal object.

In accordance with my invention, therefor, I provide a sheet ofsubstantial character adapted to give to the enclosed article mechanicalprotection from dirt, abrasion by exterior objects and the like, which,whileritmbodies stratum impenetrable by oil .tolpreventf escapijthereof,presents to the articleea-,zsurfac'ln'fusd with a cor-` rosioninhibiting pifofgliit.4l This product is to a degree analogous tothe oilitself and, while exbe dissipated through the passageways. For thispurpose the sheet, while generally flat, may have a rugose surface,preferably provided by resilient embossments such as are secured by thecraping process with' the important advantage that if anexterior-pressure on the package tends to push away or wipe off the oilfilm at the location of the pressure, on release of the pressure theresilient reaction tends to re-establish the film. This action might bereferred to somewhat metaphoricallyas a pumping-back eect.

In th'e preferred form as diagrammatically illustrated in theaccompanying drawings, the wrapper includes a paper base 6, desirably asulphate kraft. a thirty-pound ream weight being suitable, the paperbeing of a chemically neutral character, the hydrogen ion concentrationas determined by test No. T435m-34 of the Technical Association of thePulp and Paper Industry (TAPPI) showing a pH value of 6.5,to 6.9. Initself such a sheet is a durable protection against exterior dirt andabrasive contacts. Its strength' and impervious character are, moreover,substancluding absorption and removal of the film, is

compatible with theslushing oil and may absorb any excess oil whilelmaintaining at all times a corrosion-resisting nlm on the metal. Themechanical contact of this infused surface with the enclosed article ispreferably such as to maintain.

between the article andthe wrapping minute passageways permittingbreathing" so.that,'for example, moisture is not trapped and confined toone locality possibly to cause corrosion, but may tially increased byits infusion with a suitable corrosion inhibiting compound. Thiscompound may include a resinoid base, as, for example, rosin or asurrogate therefor, which is free, however, from deleterious ingredients(the meaning ofthis limitation will hereinafter more fully appear) andan oil or like plasticizing ingredient which may be of the same generalcharacter as the slushing oil and may alsohave added thereto a corrosioninhibiting agent. The compound might thus be termed a tempered resinwhich, while solid at ordinary temperatures, is not brittle but capableof flexing easily with the paper, is amorphous and soft in the senseth'at it has no hard fractured edges and is free of crystallineparticles which might scratch highly finished metal. A compound of thisnature which I have used in practicescftens at about 200 rF. to form arather viscous liquid and flows quite freely at about 300 F. Itisneutral, the pH value being from 6.5 to 7.5. Water soluble acidity isless than 0.01% equivalent sulphur trioxide when determined inaccordance with VTAPPI test No. T428m-40. The sulphate (S04 test)chloride (Cl test) content combined is less than 0.1% determined inaccordance with the methods of the American Society for TestingMaterials. The material may thus be termed neutral to steel; that is, itis inert as faras its action on steel when in contact therewith isconcerned. It should be noted that the tempering or plasticizing agent,if an oil, is of1non-dryingjchr acter. Both it and the resinoid aresubstantially unalterable under the conditions of use. That is, theinfusing compound as such is chemically inert and unalterable during thepreparation of the sheet and the subsequent use thereof, no oxidization,polymerization or condensation being involved. Thus in the case ofmaterial as practically used by me a live-hour accelerating aging of aspecimen of the wrapping sheet in an oxygen bomb resulted in nodetrimental eil'ect on the impregnation.

The impregnating material may be applied tothe sheet in a fused ormelted condition at from 300 to 350 F. and is diffused into the body ofthe sheet conveniently by the process disclosed in the patent toWheildon No. 1,595,637 and the sheet is conveniently craped as thereindescribed in the same operation to provide a rugose sheet with amultiplicity of irregular resilient embossments. It may be noted thatAthe Wheildon patent above referred to specifically refers to the useofasphalt and to prevent misunderstanding it may be well to state herethat asphalt as commonly known is entirely unsuitable for the purposesof a mapping of the type under consideration- The infused sheet preparedin this manner .has the tempered resinoid absorbed into the body thereofinto the spaces between the fibers, residual air and moisture in thepaper being substantially entirely eliminated and displaced thereby, andhas a non-tacky surface as indicated by the fact that it may be rolledup without protective sheets between the turns.

In Fig. 2, I have indicated by stippling the infused character of thesheet and have shown very diagrammatically at l the resilientembossments provided by the craping operation.

One face of the sheet 6, opposite to the one which in use is applied tothe article, is provided with a stratum impenetrable by oil. Theeffectiveness of such a stratum may be determined by the turpentinepenetration test, TAPPI test No. T454m-42, and although for certainpurposes a lesser degree of resistance may be acceptable, I prefer toprovide sucha stratum that the wrapper will not allow turpentine topenetrate through it in less than an average'of 1800 seconds. In theexam-ple of the invention chosen for purposes of illustration thisoil-resisting stratum, or oil barrier as it may be called, is apre-formed sheet or layer i0 of cellulose acetate sheeting which isadhered by a suitable adhesive, which may be the same as the infusingcompound above referred to, to a kraft paper sheet 12. In Fig. 2 I havenot attempted to illustrate separately the uniting layer of adhesive.The assembly of the sheets I0 and l2 may be craped to permit it toexpand in the same manner as the base layer 6 and may be united theretoadhesively by a connecting coating I4 of the fusible corrosioninhibiting compound above described which makes a homogeneous union withthe impregnant of the base layer I. The joint provided thereby will notseparate as the result of normal manipulations of wrapping.

'111e exterior kraft sheet l2 when used and the uniting medium Ilprovide an additional thickness for the wrapping, increasing itsmechanical protective capacity and the sheet I2 provides a surface towhich gummed labelsv and the like may be adhesively united.

The infused sheet 6 is not absorbent in the sense that untreated paperwould be, and hence when applied to an oil-slushed article has nosubstantial tendency to blot up or dissipate the oil nlm. nor willtherebe va resultant oil saturalit will not in itself cause corrosionbut will maintain the protective oil covering. The oil barrier Il. suchas the cellulose acetate film described. checks such migration of theoil as might cause dissipation thereof in such manner as to causeimpairment of the protective film on the wrapped article or to causesmearing of exterior objects.

An important advantage arises from the craped character ofthe sheet asdescribed in that, as diagrammatically shown in Fig, 2. when itispresented to the surface of the wrapped article A the crests of thecrapings l bear on the oil-coated surface and define between them openand irreguiar passageways. Thus moisture on the exterior of the articleis not trapped and retained in one spot, where it might possibly piercethe oil film and cause corrosion but maybe dissipated through thepassageways, which allow the wrapped article to breathe The embossments8 provided by the craping process are of a resilient nature and, ifflattened A down, tend to return to their original form. Thus if thewrapped articleis subjected to pressure which tends to push or wipe awaythe oil lm at one locality, on release of this pressure the expansion ofthe crapings will tend to draw back the oil with a pumping action to itsoriginal position. As an indication of the effectiveness of the presentwrapper, which I attribute in substantial part to this action, theresult of the following test may be cited. A highly polished steel.lournal approximately 2 niches in diameter and having a 11/2 micro-inchfinish was slushed with oil and vwrapped with material as hereindescribed and then the package subjected to a pressure of 3000 poundsper square inch. When exposed in a humidity cabinet to a very highdegree of temperature and relative humidity, no corrosion was observed.I know of no so-called greaseproof paper consisting of a fiat sheetwith'oil-resisting iinpregnation which would attain a like result.

7 'Ihe advantages of resistance to shock due to its resilience and ofadaptability to irregular articles due to its differential expansibilityare also attained when the wrapper-is craped.

The material is ilexible and adapted to be wrapped or folded about anarticle in the same manner as any heavy wrapping paper and may be tornfrom a roll as desired by the use of ordinary ledger blades. I havealready referred to the fact that the infused surface is non-tacky inthe sense that the wrapper may be rolled up without a protective sheeton this surface. yet easily unrolled, with separation of the turns ofthe roll. and without objectionable offset of infusing l material on theunderlying turn of the roll which, in the case of a wrapper. as shown inFig. 2, would be the plain kraft sheet l2.

While I have referred to the material as a wrapper such as is formedfrom the ilat into shape around an article to be enclosed, it may bepreformed into bags, envelopes, sheaths, cots or`the like as conveniencemay dictate.

I am aware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive, as in fact clear ,in severalmatters from the description itself. Reference is to be had to theappended claims to indicate those principles of the inventionexemplified by theparticular embodiment described and which I desire tosecure by LettersPatent.

I claim: l

1. A flexible sheet for wrapping oil-slushed metal articles comprising acraped paper basehaving absorbed into the body thereof a normally solid,flexible impregnant and comprising a neutral resinoid and a permanentoil ingredient compatible with the slushing oil, the base presenting at'one side of the sheet for contact with the article a rugoseimpregnant-bearing non-abrasive and non-tacking surface, the sheethaving a stratum impenetrable by oil exterior to said surface, whichstratum is undulating topermit its expansion and contractionl with thebase.

2. A flexible sheet for wrapping oil-slushed metal articles comprisinga. craped paper base having absorbed into the body thereof a normallysolid, flexible impregnant and comprising a neutral resinoid and apermanent oil ingredient com patible with the slushing oil, the basepresenting at one sid-e of the sheet for contact with the article arugose impregnant-bearing non-abrasive and non-tacking surface, andhaving united to the other face of saidbase a craped assembly comprisinga` paper exterior sheet and an interior sheet impenetrable by oil.

3. A iiexible sheet for wrapping oil-slushed metal articles comprising apaper base having absorbed into` the body thereof a normally solid,

oil and comprising a neutral resinoid and a permanent oil ingredient,the base presenting at one side of the sheet for contact with the oilyarticle to be Wrapped an impregnant-bearing, non-abrasive andnon-tacking surface, thebase being sive and non-tacking surface, thebase being genflexible lmpregnant compatible with the slushing erallyflat but the surface being irregular to define a multiplicity of bearingprojections and relatively depressed breathing channels, the sheet`comprising, exteriorly of the base, a stratum impenetrable by oil.

` MARSHALL W. FORREST.4

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,882,715 Angler Oct. 18, 19321,984,910 Angler Dec. 1.8, 1934 2,069,778 Rowe c Feb. 9, 1937 2,291,838Shoan Aug. 4, 1942 FOREIGN PATENTS Number Country Date 9,787 GreatBritain 1907 580,921 Germany July 18, 1933

